The present invention relates to a process for producing a chlorohydrin by reacting an olefinically unsaturated compound with chlorine in the presence of water.
East German Patent 144,907 discloses a process for the continuous production of aqueous propylene chlorohydrin by reacting propylene and chlorine in the presence of water in a bubble column. The bubble column is completely filled with the reaction mixture. The gas volume should be minimized or gas avoided in the bubble column. The reaction products are removed from the column via a conical head section. They are separated into an aqueous phase and a gaseous phase only outside the bubble column. Unfortunately, a temperature and pressure gradient is observed over the reactor, i.e., the temperature and pressure are not constant over the entire length of the column. Furthermore, the process water demand in the reaction is very high. Moreover, the organic products do not readily evaporate but an organic liquid phase may be formed which increases the tendency to the formation of by-products.
Published European Patent Application 0,016,433 discloses that in known processes for producing chlorohydrins chlorine and propylene are reacted continuously in a large excess of water at ambient or slightly elevated pressure. A portion of the solution of propylene chlorohydrin containing hydrochloric acid which is produced is recycled to the reactor because chlorine is said to be much more soluble in aqueous hydrochloric acid than in water. European Patent Application 0,0.16,433 suggests a continuous production of propylene chlorohydrin by reacting chlorine and propylene in an aqueous solution at 20.degree. C. to 80.degree. C. wherein chlorine, propylene and water are reacted in a co-current stream at a pressure between 15 and 40 bar without recycling a portion of the reaction product mixture. Propylene and chlorine are used in a molar ratio of (1.0 to 2.0):1. The amount of water is 10 to 50 liters per kg of chlorine. The starting materials are fed in gaseous or liquid form in a fine distribution into a tubular reactor. The European Patent application recommends avoiding a gas phase in the reactor in order to reduce the amount of by-products that are formed in the reaction. Unfortunately, the organic products do not readily evaporate but an organic liquid phase may be formed which increases the tendency for the formation of by-products.
French Patent 1,557,589 discloses a process for producing dichlorohydrins by dispersing allyl chloride in a large amount of water and then contacting it with chlorine. It is suggested to conduct the reaction in a reactor with rotating pallets. Unfortunately, the process water demand is very high in the suggested process. The organic products are practically insoluble in water and form an organic phase in which secondary reactions take place. This organic phase has to be separated rapidly from the aqueous solution which contains the dichlorohydrins. However, secondary reactions wherein by-products are formed are highly undesirable.
DERWENT abstract AN 91-226460, abstracting JP-A-3,145,481 suggests the preparation of epichlorohydrins by reacting 2,3-dichloro-1-propanol and/or 1,3-dichloro--2-propanol with an alkaline solution. However, this reaction makes use of other starting materials.
In view of the deficiencies of the processes disclosed in the prior art, it is desirable to provide an improved process for producing chlorohydrins.